1. Field of the Invention
This invention relates to medical devices. More particularly, this invention relates to a test harness for evaluation of control circuitry in medical devices that perform tissue ablation.
2. Description of the Related Art
Ablation of body tissue using electrical energy is known in the art. The ablation is typically performed by applying alternating currents to the electrodes, for example radiofrequency (RF) energy, at a sufficient power to destroy target tissue. Typically, the electrodes are mounted on the distal tip of a catheter, which is inserted into a subject. The distal tip may be tracked in a number of different ways known in the art, for example by measuring magnetic fields generated at the distal tip by coils external to the subject.
A known difficulty in the use of radiofrequency energy for tissue ablation, e.g., cardiac tissue ablation, is controlling local heating of tissue. Precise control of the amount of RF energy applied by the catheter electrode is important in achieving consistent therapeutic results while avoiding excessive injury to surrounding tissues.
Self-regulating tissue ablators have been proposed to achieve the desired control. For example, PCT International Publication WO9600036 discusses ablation of body tissue in which ablating energy is conveyed individually to multiple emitters in a sequence of power pulses. The temperature of each emitter is periodically sensed and compared to a desired temperature established for all emitters to generate a signal individually for each emitter based upon the comparison. The power pulse to each emitter is individually varied, based upon the signal for that emitter to maintain the temperatures of all emitters essentially at the desired temperature during tissue ablation.